The present invention relates to a frame for a press, and more particularly to a frame which prevents a press bed and columns from deforming under a working load.
A prior art frame for a straight-side press, as shown in FIG. 7, has a frame structure including a bed 1; columns 2 set up in front and rear on both the left and right of the bed 1, that is, on the four corners of the bed; a crown 3 disposed on the columns 2; and tie rods 4 for fastening together the bed 1, the columns 2 and the crown 3. A bolster 5 is mounted on the bed 1 in the center thereof and is bolted to the bed 1, and a slide 6 is so constructed that it can move up and down relative to the bolster 5 within the columns 2.
Pressing is performed between lower and upper dies 7 and 8 respectively provided on the bolster 5 and the slide 6.
When the press is under a working load, the bed 1 and the slide 6 deflect in the vertical direction by distances .delta..sub.1 and .delta..sub.2, respectively, as shown by dashed line and the columns 2 deform inwardly by a distance .delta..sub.3 toward the center of the press under the influence of the deflection of the bed.
The deformation of the bed and columns during the press operation will have the effect of lowering the dynamic accuracy of the press, and particularly the deformation of the columns deforms the guiding surface of the slide, thereby causing the slide movement to devert from its intended path, resulting in a lowering of the accuracy of manufacture of products.
The prior art method of bolting the bolster to the bed does not decrease the deflection of the bed and the deformation of the columns.